Patent GB-683291-A (GB)
Title: Improvements in or relating to a sewing machine
IPC: D05B57/14
Filed: 1949-12-15
Abstract: 683,291. Sewing-machines. MEFINA SOC. ANON. Dec. 15, 1949 [Dec. 20, 1948], No. 32197/49. Class 112. In a zig-zag sewing-machine the lateral movements of the needle and the feed movements are controlled by separate changeable cams on a common shaft; in the machine described the direction and amount of feed and the amplitude of needle vibration may also be adjusted manually, and the neutral position of the needle-bar may be adjusted laterally. The cams 19, 20, Fig. 6, with an intermediate spacer, are slidable from the top on to the hub of a flanged member fixed on a vertical shaft 11 driven by worm gearing from the main shaft 4 of the machine; a pin 23 on the driving member prevents rotation of the cams relatively to it, and a nut screwed on the end of the hub of the member secures the cams in place. Needles, vibrating laterally.-The needle-bar 7, Fig. 5, is carried by a gate oscillated on a vertical axis 26 by a member 29 against the action of a tension spring 31; the other end of the member 29 has a finger engaging a surface 32 on an arm 37 which is pivoted at 50 on a spring-biassed stationary lever 38 and which carries a pin 51 whereby it may be rocked by the cam 19 to produce the lateral movements of the needle. The member 29 can be shifted along the arm 37, to vary the amplitude of lateral movement of the needle produced by any given cam 19, by a finger lever 33 mounted on the bearing of the shaft 11; in the position shown, with the finger on member 29 in line with the pivot 50, no lateral movement of the needle is produced, and the mechanism may be put completely out of action by moving the finger a little beyond the pivot 50, whereupon the force of the spring 31 rocks the arm 37 clear of the cam against a stop n on the lever 38. The lever 38 serves to adjust the mean or resting position of the needle-bar laterally of the line of stitching by shifting the pivot 50; it is adjusted by a finger-wheel M having a spiral groove 41 in which engages a lug 40 on a member adjustably fixed to the lever 38. Feed, varying and reversing.-The stroke and direction of action of the feed mechanism, which is described in Specification 683,292, is determined by the direction of a guide slot formed in a member carried on the lower end of a vertical spindle 89, Fig. 6, which is biassed towards one extreme position by a torsion spring. The shaft 89 carries two short arms, one bearing an adjustable abutment member 110 and the other having an abutment surface 92 for engagement with a pin 93 on a lever 94 which is pivoted at 97 on a lever 96 pivotally mounted on the frame at 100 and which has at the other. end a pin 99 engaging the cam 20; a spring 121 biasses the mechanism to keep the pin 93 in contact with the surface 92 and to hold the pin 99 clear of the cam. The mechanism is controlled by a fingerlever a having a forked end straddling and cscillating on a bearing of the main shaft 4; this lever projects through a slot in the arm of the machine, and its movement may be limited, or it may be held in one position, by two adjustable stops. In the upper part of the range of movement of the lever a a cam surface on its tail engages the abutment 110 on the shaft 89 to hold the latter in any desired position of adjustment; in the lowest position of the lever another arm 109 on it engages the end of the lever 96 to carry the pin 99 against the cam so that the position of the shaft 89 is controlled automatically by the cam by means of the arm 94. Needles, driving.-The needle-bar 7 is driven from the shaft 4 by the usual pitman 54, Fig. 5, which slidably engages a pin 56 projecting laterally from a block fixed on to the needle-bar; lateral movement of the pitman is prevented by a forked end thereof sliding on a fixed plate 60. Specifications 683,379 and 683,380 also are referred to.